Walt Disney was already a well-known creative genius - the creator of Mickey Mouse and the 1938 feature-length cartoon Snow White and the Seven Dwarfs - when he had an idea to create Disneyland, his famed Anaheim, California, amusement park.

'All my life I heard him talk about doing this park, from the time I was five,' daughter Diane Disney Miller said in a documentary about Disneyland.

'The dream just grew,' she says in the film, adding that by the time she turned 21, her father had finally done it, at a cost of $17 million.

In this Jan. 22, 2015, file photo, visitors follow Mickey Mouse for photos at Disneyland in Anaheim, Calif. Disneyland, the original theme park, opened in 1955.

8203;On opening day, July 17, 1955, everything that could go wrong did, according to those who helped build the amusement park.

That day - it became known as 'Black Sunday' - more people showed up than the park could accommodate and mountains of trash stood uncollected. That same day there was a strike by plumbers in Anaheim, so organizers were forced to choose between working bathrooms or working water fountains. Rivers in the park that had been filled the night before, ran dry.

Disney was deeply disappointed, but he and his team kept improving the park, adding new rides and characters, and a giant monorail system in 1959.

The monorail, which encircles Disneyland in Anaheim, Calif., makes its way past a McDonald';s restaurant outside the amusement park Thursday, May 23, 1996.

Expanding on his dream, work began on an even bigger amusement park in Orlando, Florida, in 1965.

Walt Disney died in 1966. Walt Disney World was opened in his honor on Oct. 1, 1971.